Method and apparatus for positioning a diagnostic or therapeutic element within the body and tip electrode for use with same

ABSTRACT

Surgical methods and apparatus for positioning diagnostic an therapeutic elements on the epicardium or other organ surface. The apparatus include a relatively short shaft and an adjustable loop structure that supports

BACKGROUND OF THE INVENTIONS

[0001] 1. Field of Inventions

[0002] The present inventions relate generally to structures forpositioning diagnostic and therapeutic elements within the body and,more particularly, to devices which are particularly well suited for thetreatment of cardiac conditions

[0003] 2. Description of the Related Art

[0004] There are many instances where diagnostic and therapeuticelements must be inserted into the body. One instance involves thetreatment of cardiac conditions such as atrial fibrillation and atrialflutter which lead to an unpleasant, irregular heart beat, calledarrhythmia.

[0005] Normal sinus rhythm of the heart begins with the sinoatrial node(or “SA node”) generating an electrical impulse. The impulse usuallypropagates uniformly across the right and left atria and the atrialseptum to the atrioventricular node (or “AV node”). This propagationcauses the atria to contract in an organized way to transport blood fromthe atria to the ventricles, and to provide timed stimulation of theventricles. The AV node regulates the propagation delay to theatrioventricular bundle (or “HIS” bundle). This coordination of theelectrical activity of the heart causes atrial systole duringventricular diastole. This, in turn, improves the mechanical function ofthe heart. Atrial fibrillation occurs when anatomical obstacles in theheart disrupt the normally uniform propagation of electrical impulses inthe atria. These anatomical obstacles (called “conduction blocks”) cancause the electrical impulse to degenerate into several circularwavelets that circulate about the obstacles. These wavelets, called“reentry circuits,” disrupt the normally uniform activation of the leftand right atria.

[0006] Because of a loss of atrioventricular synchrony, the people whosuffer from atrial fibrillation and flutter also suffer the consequencesof impaired hemodynamics and loss of cardiac efficiency. They are alsoat greater risk of stroke and other thromboembolic complications becauseof loss of effective contraction and atrial stasis.

[0007] Although pharmacological treatment is available for atrialfibrillation and flutter, the treatment is far from perfect. Forexample, certain antiarrhythmic drugs, like quinidine and procainamide,can reduce both the incidence and the duration of atrial fibrillationepisodes. Yet, these drugs often fail to maintain sinus rhythm in thepatient. Cardioactive drugs, like digitalis, Beta blockers, and calciumchannel blockers, can also be given to control the ventricular response.However, many people are intolerant to such drugs. Anticoagulant therapyalso combats thromboembolic complications, but does not eliminate them.Unfortunately, pharmacological remedies often do not remedy thesubjective symptoms associated with an irregular heartbeat. They also donot restore cardiac hemodynamics to normal and remove the risk ofthromboembolism.

[0008] Many believe that the only way to really treat all threedetrimental results of atrial fibrillation and flutter is to activelyinterrupt all of the potential pathways for atrial reentry circuits.

[0009] One surgical method of treating atrial fibrillation byinterrupting pathways for reentry circuits is the so-called “mazeprocedure” which relies on a prescribed pattern of incisions toanatomically create a convoluted path, or maze, for electricalpropagation within the left and right atria. The incisions direct theelectrical impulse from the SA node along a specified route through allregions of both atria, causing uniform contraction required for normalatrial transport function. The incisions finally direct the impulse tothe AV node to activate the ventricles, restoring normalatrioventricular synchrony. The incisions are also carefully placed tointerrupt the conduction routes of the most common reentry circuits. Themaze procedure has been found very effective in curing atrialfibrillation. However, the maze procedure is technically difficult todo. It also requires open heart surgery and is very expensive. Thus,despite its considerable clinical success, only a few maze proceduresare done each year.

[0010] Maze-like procedures have also been developed utilizing catheterswhich can form lesions on the endocardium to effectively create a mazefor electrical conduction in a predetermined path. Exemplary cathetersare disclosed in commonly assigned U.S. Pat. No. 5,582,609. Typically,the lesions are formed by ablating tissue with an electrode carried bythe catheter. Electromagnetic radio frequency (“RF”) energy applied bythe electrode heats, and eventually kills (i.e. “ablates”), the tissueto form a lesion. During the ablation of soft tissue (i.e. tissue otherthan blood, bone and connective tissue), tissue coagulation occurs andit is the coagulation that kills the tissue. Thus, references to theablation of soft tissue are necessarily references to soft tissuecoagulation. “Tissue coagulation” is the process of cross-linkingproteins in tissue to cause the tissue to jell. In soft tissue, it isthe fluid within the tissue cell membranes that jells to kill the cells,thereby killing the tissue.

[0011] Catheters used to create lesions (the lesions being 3 to 15 cm inlength) typically include a relatively long and relatively flexible bodyportion that has an electrode on its distal end. The portion of thecatheter body portion that is inserted into the patient is typicallyfrom 23 to 55 inches in length and there may be another 8 to 15 inches,including a handle outside the patient. The proximal end of the catheterbody is connected to the handle which includes steering controls. Thelength and flexibility of the catheter body allow the catheter to beinserted into a main vein or artery (typically the femoral artery),directed into the interior of the heart, and then manipulated such thatthe electrode contacts the tissue that is to be ablated. Fluoroscopicimaging is used to provide the physician with a visual indication of thelocation of the catheter.

[0012] Catheter-based soft tissue coagulation has proven to be asignificant advance in the medical arts generally and in the treatmentof cardiac conditions in particular. Nevertheless, the inventors hereinhave determined that catheter-based procedures are not appropriate inevery situation and that conventional catheters are not capable ofreliably forming all types of lesions. One lesion that has proven to bedifficult to form with conventional catheters is the circumferentiallesion that is used to isolate a pulmonary vein and cure ectopic atrialfibrillation. Lesions that isolate the pulmonary vein may be formedwithin the pulmonary vein itself or in the tissue surrounding thepulmonary vein. These circumferential lesions are formed by dragging atip electrode around the pulmonary vein or by creating a group ofinterconnected curvilinear lesions one-by-one around the pulmonary vein.Such techniques have proven to be less than effective because they areslow and gaps of conductive tissue can remain after the procedure. Itcan also be difficult to achieve adequate tissue contact withconventional catheters.

[0013] Endocardial lesions to isolate pulmonary veins have also beenformed as a secondary procedure during a primary open heart surgicalprocedure such as mitral valve replacement. A surgical soft tissuecoagulation probe is used to form the endocardial lesions after theheart has been opened, either before or after the valve replacement.This technique does, however, increase the amount of time the patient ison pulmonary bypass, which can be undesirable.

[0014] Accordingly, the inventors herein have determined that a needexists for surgical methods and apparatus that can be used to createlesions around bodily structures and, in the context of the treatment ofatrial fibrillation, around a pulmonary vein without increasing theamount of time that the patient is on pulmonary bypass.

SUMMARY OF THE INVENTIONS

[0015] Accordingly, the general object of the present inventions is toprovide methods and apparatus that avoid, for practical purposes, theaforementioned problems. In particular, one object of the presentinventions is to provide surgical methods and apparatus that can be usedto create lesions around a pulmonary vein or other body structure in amore efficient manner than conventional apparatus. Another object of thepresent inventions is to provide surgical methods and apparatus that maybe used to create lesions around a pulmonary vein without placing thepatient on pulmonary bypass or increasing the amount of time that thepatient is on pulmonary bypass when a related procedure is beingperformed. Still another object of the present inventions is to performa diagnostic or therapeutic procedure, such as the coagulation of tissuearound a body structure, without effecting collateral tissue that is nottargeted for the procedure.

[0016] In order to accomplish some of these and other objectives, asurgical device in accordance with a present invention includes arelatively short outer member, a relatively short shaft located at leastpartially within the relatively short outer member and slidable relativeto the relatively short outer member, and an operative element on thedistal portion of the relatively short shaft. The distal portion of therelatively short shaft is adapted to be connected to the distal portionof the relatively short outer member such that the distal portion of theshaft member will form a loop.

[0017] In order to accomplish some of these and other objectives, asurgical device in accordance with a present invention includes arelatively short outer member, a relatively short shaft located at leastpartially within the relatively short outer member and slidable relativeto the relatively short outer member, a control element defining adistal portion connected to the distal portion of the relatively shortshaft and a proximal portion extending toward the proximal portion ofthe relatively short outer member, and an operative element on thedistal portion of the relatively short shaft. The distal portion of therelatively short shaft may be used to form a loop.

[0018] In order to accomplish some of these and other objectives, asurgical; device in accordance with a preferred embodiment of a presentinvention includes a relatively short shaft and a distal member having aflexible region and a malleable region and an operative element carriedby the distal member. Preferably, the distal tip assembly may, ifdesired, also include a pull wire that facilitates the formation of aloop.

[0019] In order to accomplish some of these and other objectives, aclamp device in accordance with a preferred embodiment of a presentinvention includes first and second curved members and a tissuecoagulation apparatus associated with the first and second curvedmembers. The curved members and tissue coagulation apparatus preferablytogether define an open region that may be positioned around a bodystructure such as one or more pulmonary veins.

[0020] Such devices provide a number of advantages over the conventionaldevices used to create lesions around pulmonary veins. For example, theoperative element carrying loops and the first and second curved membersmay be positioned around a pulmonary vein (or veins) on the epicardialsurface in accordance with inventive methods disclosed herein. Acontinuous transmural lesion that will isolate the vein may then becreated while the heart is beating. The heart need not be opened andpulmonary bypass is not required. As such, the present devicesadvantageously allow curative lesions to be formed around pulmonaryveins without the difficulties associated with catheter-based proceduresor the time on pulmonary bypass required by conventional surgicalprocedures.

[0021] In order to accomplish some of these and other objectives, a maskelement for masking an operative element supported on a support body inaccordance with a present invention includes a main body with a sidewall defining an interior bore and a side wall opening. The maskelement, which is preferably formed from thermally and electricallyinsulating material, is adapted to be positioned on the supportstructure such that a portion of the operative element is aligned withthe side wall opening and a portion of the operative element is coveredby the side wall. When the support structure is positioned with the sidewall opening (and exposed portion of the operative element) facing thetarget tissue region, the remainder of the operative element will becovered by the side wall. As such, the present mask element protectsnon-target collateral tissue from being damaged, sensed or otherwiseaffected by the operative element.

[0022] The above described and many other features and attendantadvantages of the present inventions will become apparent as theinventions become better understood by reference to the followingdetailed description when considered in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Detailed description of preferred embodiments of the inventionswill be made with reference to the accompanying drawings.

[0024]FIGS. 1A and 1B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

[0025]FIG. 1C is a partial section view of the distal portion of theshaft illustrated in FIG. 1B.

[0026]FIG. 2 is a side view of the outer member illustrated in FIG. 1B.

[0027]FIG. 3 is an end view of the outer member illustrated in FIG. 1B.

[0028]FIG. 4 is a section view taken along line 44 in FIG. 1B.

[0029]FIG. 5 is a perspective view showing the surgical deviceillustrated in FIGS. 1A-1C being used in a surgical procedure involvingthe heart.

[0030]FIGS. 6A and 6B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

[0031]FIG. 7A is a plan view of a portion of a surgical device inaccordance with a preferred embodiment of a present invention.

[0032]FIG. 7B is a partial section view of the distal portion of theshaft illustrated in FIG. 7A.

[0033]FIGS. 8A and 8B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

[0034]FIG. 8C is a partial section view of the distal portion of theshaft illustrated in FIG. 8B.

[0035]FIG. 9A is a perspective view of the exemplary anchoring deviceillustrated in FIG. 8B.

[0036] FIGS. 9B-9D are perspective views of other exemplary anchoringdevices.

[0037]FIG. 10 is a side, partial section view of a pull wire guide andelectrode support structure in accordance with a preferred embodiment ofa present invention.

[0038]FIG. 11 is a perspective view of the pull wire guide illustratedin FIG. 10.

[0039]FIG. 12 is a perspective view of a pull wire guide in accordancewith a preferred embodiment of a present invention.

[0040]FIGS. 13A and 13B are partial plan views together showing asurgical device in accordance with a preferred embodiment of a presentinvention.

[0041]FIG. 14 is a plan view of a surgical device in accordance with apreferred embodiment of a present invention.

[0042]FIG. 15 is a section view taken along line 15-15 in FIG. 14.

[0043]FIG. 16 is a section view taken along line 16-16 in FIG. 14.

[0044]FIG. 17A is a partial side view of a distal structure that may beused in conjunction with a surgical device such as that illustrated inFIGS. 14 and 17C.

[0045]FIG. 17B is a side view of another distal structure that may beused in conjunction with a surgical device such as that illustrated inFIGS. 14 and 17C.

[0046]FIG. 17C is a plan view of a surgical device in accordance with apreferred embodiment of a present invention.

[0047]FIG. 17D is a perspective view of a tip electrode in accordancewith a preferred embodiment of a present invention.

[0048]FIG. 17E is a side view of the tip electrode illustrated in FIG.17D.

[0049]FIG. 17F is a partial perspective view of another tip electrode.

[0050]FIG. 18 is a plan view showing a portion of a surgical device andelectrode identification system in accordance with a preferredembodiment of a present invention.

[0051]FIG. 19 is an exploded perspective view of a mask element inaccordance with a preferred embodiment of a present invention.

[0052]FIG. 20 is an exploded side view of the mask element illustratedin FIG. 19 in combination with a surgical device that carries aplurality of electrodes.

[0053]FIG. 21 is a front plan view of a clamp device in accordance witha preferred embodiment of a present invention.

[0054]FIG. 22 is an enlarged rear plan view of a portion of the clampdevice illustrated in FIG. 21.

[0055]FIG. 23 is a section view taken along line 23-23 in FIG. 21.

[0056]FIG. 24 is a section view taken along line 24-24 in FIG. 21.

[0057]FIG. 25 is a plan view of a clamp device in accordance with apreferred embodiment of a present invention.

[0058]FIG. 26 is a perspective view of a portion of a heart with lesionsformed in accordance with a therapeutic method in accordance with apresent invention.

[0059]FIG. 27 is a perspective view of a portion of a heart with alesion formed in accordance with a therapeutic method in accordance witha present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] The following is a detailed description of the best presentlyknown modes of carrying out the inventions. This description is not tobe taken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions.

[0061] The detailed description of the preferred embodiments isorganized as follows:

[0062] I. Loop Structures With Coupling Devices

[0063] II. Loop Structures With Coupling Devices And Pull Wires

[0064] III. Loop Structures With Pull Wires

[0065] IV. Operative Elements, Temperature Sensing And Power Control

[0066] V. Operative Element Identification

[0067] VI. Masking

[0068] VII. Clamp Devices

[0069] VIII. Methods

[0070] The section titles and overall organization of the presentdetailed description are for the purpose of convenience only and are notintended to limit the present inventions.

[0071] This specification discloses a number of structures, mainly inthe context of cardiac ablation, because the structures are well suitedfor use with myocardial tissue. Nevertheless, it should be appreciatedthat the structures are applicable for use in therapies involving othertypes of soft tissue. For example, various aspects of the presentinventions have applications in procedures concerning other regions ofthe body such as the prostate, liver, brain, gall bladder, uterus andother solid organs.

[0072] I. Loop Structures with Coupling Devices

[0073] As illustrated for example in FIGS. 1A and 1B, a surgical device10 in accordance with a preferred embodiment of a present inventionincludes a shaft 12 that is preferably formed from two tubular parts, ormembers. The proximal member 14 is attached to a handle 16 while thedistal member 18, which is shorter than the proximal member, carries anoperative element such as the illustrated plurality of spaced electrodes20. The proximal member 14 is typically formed from a biocompatiblethermoplastic material that is thermally and electrically insulating,such as a Pebax® material (polyether block amide). The distal member 18is typically formed from a softer, more flexible biocompatiblethermoplastic material that is also thermally and electricallyinsulating, such as Pebax® material, polyethylene, or polyurethane. Theproximal and distal members, which are about 5 French to about 9 Frenchin diameter, are preferably either bonded together with an overlappingthermal bond or adhesively bonded together end to end over a sleeve inwhat is referred to as a “butt bond.”

[0074] The shaft 12 in the exemplary surgical device 10 extends throughthe interior bore of an outer member 22 in the manner illustrated inFIGS. 1A and 1B. The outer member 22 is preferably a tubular structurethat includes a locking device 24, such as the illustrated Toughy Borstfitting, at the proximal end to fix the position of the shaft 12relative to the outer member. The outer member 22 also preferablyincludes a flared inner surface 23 (FIG. 2) to facilitate movement ofthe electrodes 20 into the outer member. Alternatively, the distal endof the outer member may be formed from relatively soft material. Withrespect to materials the outer member 22 may be formed from a thermallyand electrically insulating biocompatible thermoplastic material such asPebax® material.

[0075] The shaft 12 and outer member 22 are both relatively short. Theterm “relatively short” is used in the present specification to describea length that is suitable for direct placement against the targetedtissue region during a surgical procedure. “Relatively long” shafts, onthe other hand, include conventional catheter shafts that are guidedthrough the vasculature to a target tissue region. In the context of thesurgical procedures involving the heart, access to the targeted tissueregion may be obtained by way of a thoracotomy, median stemotomy, orthoracostomy. As such, the length of the shaft 12 is preferably betweenabout 6 inches and about 30 inches, with the proximal member 14 beingbetween about 3 inches and about 20 inches, and the distal member 18being between about 3 inches and about 20 inches. The length of theouter member 22 is only about 2 inches to about 10 inches.

[0076] A loop may be formed by securing the distal end of the shaft 12to the distal end of the outer member 22 and a fastening apparatus isprovided that allows the distal ends to be releasably secured to oneanother. The fastening apparatus in the illustrated embodiment consistsof a hook 26 on the distal end of the outer member 22 and an eyelet 28on the distal end of the shaft 12. Referring more specifically to FIGS.2 and 3, the hook 26 is mounted on a cylindrical base 30 that is itselfmounted on the exterior of the distal end of the outer member 22. Thebase 30, which along with the hook 26 is preferably formed from metal orplastic, may be secured to the outer member 22 through the use ofadhesive, welding or other suitable methods. The eyelet 28 is anchoredto a flexible internal core wire 32 (FIG. 4) that may be formed fromresilient inert wire, such as stranded or solid nickel titanium(commercially available under the name Nitinol), braided Spectran® orKevlar® fibers, or common suture materials. Suitable materials for theeyelet 28 include Nitinol, 17-7 stainless steel, Spectran® and Kevlar®.It should also be noted that the locations of the hook 26 and eyelet 28may be reversed.

[0077] The core wire 32 is anchored at the proximal end of the shaft 12,while the core wire and eyelet 28 are both anchored at the distal end ofthe shaft. Referring to FIG. 1C, the proximal portion of the eyelet 28and the distal portion of the core wire 32 are secured to one anotherwith a crimp tube 27 in the exemplary embodiment. The crimp tube 27 issoldered, welded or otherwise bonded to a tip anchor 29 that is mountedon the distal end of the distal member 18. An insulating sleeve 31 isalso provided along the length of the distal member 18.

[0078] Although the core wire 32 is preferably circular incross-section, the portion of the core wire within the distal member 18may have a rectangular (or other non-circular shape) cross-section inorder to control the bending plane of the distal member. This techniqueis especially useful when portions of the electrodes 20 are masked usingone of the techniques described in Section VI below.

[0079] As illustrated for example in FIG. 5, one use of the exemplarysurgical device 10 involves the creation of an epicardial lesion arounda pair of pulmonary veins PV. The shaft 12 and outer member 22 aredirectly inserted into the patient's chest and the shaft distal member18 may be threaded around a pair of pulmonary veins PV with hemostats orother surgical instruments. An adjustable loop 33 is formed by placingthe eyelet 28 over the hook 26. The loop 33 may be tightened around thepulmonary veins PV by holding the outer member 22 and pulling the shaft12 in the proximal direction. Relative movement of the shaft 12 andouter member 22 can be prevented with the locking device 24 to maintainthe loop 33 in the desired size. Once the loop 33 has been accuratelypositioned, some or all of the electrodes 20 may be used to create atransmural epicardial lesion around the pulmonary veins PV. Additionalinformation concerning methods of creating epicardial lesions isprovided in Section VIII below.

[0080] In order to allow the distal member 18 to be tightly threadedaround a relatively small structure such as a pulmonary vein, the distalmember is preferably very flexible. As used herein, the term “veryflexible” refers to distal members which are more flexible than thedistal portions of conventional diagnostic and steerableelectrophysiology catheters, which must be stiff enough to forceelectrodes against tissue.

[0081] The exemplary handle 16 illustrated in FIG. 1A consists of twomolded handle halves and is provided with strain relief element 36 and aPC board 38. As discussed in greater detail in Section IV below, thereis a temperature sensor associated with each longitudinal edge of theelectrodes 20 in the illustrated embodiment. Signal wires 41 (FIG. 4)are connected to the electrodes 20 and signal wires 42 are connected tothe temperature sensors. The signal wires are passed in conventionalfashion through a lumen extending through the shaft 12 to the PC board38. The PC board 38 is, in turn, electrically coupled to a connectorthat is received in a port at the proximal end of the handle 16. Theconnector plugs into a source of RF coagulation energy.

[0082] Another exemplary device, which is generally represented byreference numeral 40, is illustrated in FIGS. 6A and 6B. Many structuralelements in the exemplary device 40 are similar to those in theexemplary device 10 and such elements are represented by the samereference numerals. For example, the exemplary device 40 includes arelatively short shaft 12 with a proximal member 14 and a distal member18 that supports a plurality of electrodes 20 or some other operativeelement. Exemplary device 40 also includes a handle 16 and a hook 26 andeyelet 28 arrangement.

[0083] The primary difference between the two surgical devices is thatthe exemplary device 40 includes a relatively short outer member 42 thatis relatively stiff. In other words, the outer member is either rigid,malleable, or somewhat flexible. A rigid outer member cannot be bent. Amalleable outer member is a outer member that can be readily bent by thephysician to a desired shape, without springing back when released, sothat it will remain in that shape during the surgical procedure. Thus,the stiffness of a malleable outer member must be low enough to allowthe outer member to be bent, but high enough to resist bending when theforces associated with a surgical procedure are applied to the outermember. A somewhat flexible outer member will bend and spring back whenreleased. However, the force required to bend the outer member must besubstantial. Rigid and somewhat flexible shafts are preferably formedfrom stainless steel, while malleable shafts are formed from annealedstainless steel. Additional information concerning malleable structuresmay be found in aforementioned U.S. application Ser. No. 09/072,872.

[0084] A rigid or somewhat flexible outer member 42 may be linear orformed with one or more bends 44 designed for a particular surgicalprocedure, as is illustrated for example in FIG. 6B. The physician mayplace bends in a malleable outer member 42 in order to facilitate properplacement of the distal end of the outer member.

[0085] II. Loop Structures with Coupling Devices and Pull Wires

[0086] It may be difficult in some instances to thread the shaft distalmember 18 around an anatomical structure such as a pulmonary vein. Assuch, the distal end of the shaft 12 may be provided with a pull wire34, as is illustrated for example FIG. 7A. The pull wire 34, which isthinner and more flexible than the shaft distal member 18, will beeasier to thread around anatomical structures. After the pull wire 34has been threaded around a pulmonary vein or other structure, and aroundthe hook 26, the pull wire may be used to pull the shaft distal member18 around the structure to form a loop. Suitable materials for the pullwire 34, which is typically more flexible than the core wire 32, includestranded Nitinol, Spectran® and Kevlar®.

[0087] The pull wire 34 may be secured to the core wire 32 with a crimptube or other suitable device in the manner illustrated, for example, inFIG. 7B. More specifically, the proximal portions of the eyelet 28 andpull wire 34 and the distal portion of the core wire 32 are secured toone another with a crimp tube 27. The crimp tube 27 is soldered, weldedor otherwise bonded to a tip anchor 29 that is mounted on the distal endof the distal member 18.

[0088] III. Loop Structures with Pull Wires

[0089] As illustrated for example in FIGS. 8A and 8B, a surgical device46 in accordance with a preferred embodiment of a present inventionincludes many structural elements similar to those in the exemplarydevices illustrated in FIGS. 1A-7B and such elements are represented bythe same reference numerals. For example, the exemplary surgical device46 includes a relatively short shaft 12 with a proximal member 14 and adistal member 18 that supports a plurality of electrodes 20 or someother operative element. The proximal end of the shaft 12 is secured toa handle 16.

[0090] As illustrated for example in FIG. 8C, a pull wire 34 similar tothat illustrated in FIGS. 7A and 7B is crimped to the core wire 32 witha crimp tube 27 and the crimp tube is secured to a tip anchor 29′ bybonding, welding or other suitable methods. Here, however, the tipanchor 29′ has a closed distal end and the pull wire 34 is threadedthrough an opening 33 in the anchor. Alternatively, the core wire 32 andpull wire 34 may be replaced with a single, continuous pull/core wire(not shown).

[0091] The exemplary surgical device 46 does not, however, include anouter member with a coupling device that secures the distal portion ofthe outer member to the shaft distal member 18. Instead, surgical device46 includes a relatively short outer member 48 with a pull wire guide50. The outer member 48 also includes a flared inner surface (not shown)or soft material at its distal end and a locking device 24, such as aToughy Borst fitting, at its proximal end to fix the position of theshaft 12. The pull wire 34 may be threaded through the pull wire guide50 to form a loop 51 and then secured to an anchoring device 52. Theloop 51 may then be adjusted by moving the shaft 12 and outer member 48relative to one another or by adjusting the pull wire 34. In oneexemplary procedure, the pull wire 34 will be threaded around a pair ofpulmonary veins prior to being threaded through the pull wire guide 50to form a loop similar to that illustrated in FIG. 5.

[0092] With respect to the physical characteristics of the outer member48, the outer member is preferably formed from relatively high durometermaterials (72D and above) such as braided or unbraided Pebax® or Nylonmaterial that is stiffer than the distal member 18 as well as thermallyand electrically insulating. The outer member 48 should also be slightlyshorter (i.e. 1 to 2 inches shorter) than the proximal member 14.

[0093] As illustrated in FIGS. 8B and 9A, the exemplary anchoring device52 includes a main body 54 that is mounted on the outer member 48, apost 56 and a cap 58. The cap 58 includes a pair of slots 60. The pullwire 34 is wound around the post 56 and then through the slots 60 toanchor it in place. The anchoring device 52 is preferably formed frommolded plastic. An alternate anchoring device 52′, with a slightlydifferently shaped cap 58′, is illustrated in FIG. 9B. Still otheranchoring devices, which are represented by reference numerals 53 and53′, are illustrated in FIGS. 9C and 9D. Here, slots 55 extend throughcaps 57 and 57′ and into the posts 56 on which the caps are mounted. Theflexibility of the plastic material allows the pull wire 34 to be pulleddown through into slot 55 and then held in place through friction andmechanical interference.

[0094] In the exemplary embodiment illustrated in FIGS. 8A-8C, the pullwire guide 50 is an eyelet or other simple loop or hook structure formedfrom metal or plastic that is mounted on a cylindrical base 62.Alternatively, as illustrated in FIGS. 10 and 11, a pull wire guide 64may be provided with a plurality of pull wire openings 66 that extendaround the periphery of the distal end of the outer member 48. Thisarrangement facilitates the threading of a pull wire through the pullwire guide 64 regardless of the rotational orientation of the outermember 48 relative to the physician and patient and also eliminates theneed for the rotational orientation to be closely monitored and/oradjusted prior to loop formation.

[0095] The exemplary pull wire guide 64 illustrated in FIGS. 10 and 11,which may be formed from metal or plastic, includes a base 68 and anoutwardly flared member 70 in which the openings 66 are located. Thebase 68 has a mounting surface 72 with a shape corresponding to that ofthe outer member on which it is mounted, i.e. cylindrical in theillustrated embodiment, and a smooth curved lip 74 that should extendinwardly from the mounting surface a distance that is at least equal tothe wall thickness of the outer member. The flared member 70 includes aplurality of supports 75 and a peripheral ring 76 that together definethe pull wire openings 66. The flared member 70 also has a smooth innersurface 78 that, together with the smooth curved lip 74, facilitatesmovement of the electrodes 20 or other operative elements through thepull wire guide 64 and into the outer member 48.

[0096] Turning to FIG. 12, the exemplary pull wire guide 80 illustratedtherein is substantially similar to the guide illustrated in FIGS. 10and 11 and similar structural elements are represented by similarreference numerals. Here, however, the peripheral ring 76 in the flaredmember 70 has been replaced by a plurality of a peripheral members 82 ina flared member 70′ that define slots 84 therebetween. The slots 84allow a pull wire to be slipped into the openings 66 instead of threadedthrough the openings. The peripheral members 82 also include curved,inwardly extending end portions 86 that prevent the pull wire fromsliding out of the openings 66 once it is located therein.

[0097] Another exemplary surgical device, which is generally representedby reference numeral 88, is illustrated in FIGS. 13A and 13B. Like theexemplary surgical device 46 illustrated in FIGS. 8A-8C, surgical device88 includes a shaft 12, with a proximal member 14 secured to handle 16and a distal member 18 that supports electrodes 20 or some otheroperative element, and a pull wire 34. However, instead of a singlerelatively short outer member, surgical device 88 includes an outermember assembly 90 with a pair of outer members 92 and 94. A loop 95 isformed by directing the shaft distal member 18 outwardly from the distalend of outer member 92 and into the distal end of the outer member 94.The pull wire 34 may be anchored with an anchoring member 52 and theshaft 12 held in place relative to the outer member 92 with a lockingdevice 24. The outer members are preferably formed from stainless steelor molded polymer material and have a inner diameter of about 7 Frenchand an outer diameter of about 10 French.

[0098] The configuration of the loop 95 formed by the distal member 18is primarily determined by the shape and relative orientation of theouter members 92 and 94. In the illustrated embodiment, outer member 92is linear and outer member 94 is curved. The outer members 92 and 94,which are held in place relative to one another by a post 96 and weld(not shown) in region 98, are oriented such that the distal ends thereofdefine an angle of about 45 degrees. Of course, the curvatures of theouter members 92 and 94, as well as the relative orientation thereof,may be adjusted to suit particular needs.

[0099] In order to facilitate formation and adjustment of the loop 95,outer member 94 includes a pull wire slot 100 and the distal ends of theouter members 92 and 94 respectively include outwardly flared portions102 and 104. The pull wire slot 100 is wide enough to allow the pullwire 34 to slide into the outer member 94, yet too narrow to allow theshaft distal member 18 to slide out of the outer member once it has beenpulled in. As such, loop 95 may be formed by advancing the shaft distalmember 18 outwardly from the distal end of the outer member 92, pullingon the pull wire 34 to bend the distal member back in the proximaldirection, sliding the pull wire into the pull wire slot 100, andpulling the distal member into the distal end of the outer member 94.

[0100] As illustrated for example in FIGS. 14-16, a surgical device 106in accordance with another preferred embodiment includes a relativelyshort shaft 108, a handle 16, and a distal section 110. The shaft 108consists of a hypo-tube 112, which is either rigid or relatively stiff(preferably malleable), and an outer polymer tubing 114 over thehypo-tube. The distal section 110 is preferably somewhat flexible, inthat it will conform to a surface against which it is pressed and thenspring back to its original shape when removed from the surface.Surgical device 106 also includes a pull wire 34. The pull wire 34 ispre-threaded between the hypo-tube 112 and outer tubing 114 and throughan aperture in the handle. Alternatively, the pull wire 34 may bethreaded through a pull wire guide in the manner described above.

[0101] Referring more specifically to FIGS. 15 and 16, the exemplarydistal section 110 preferably includes a spring member 116, which ispreferably either a solid flat wire spring (as shown), a round wire, ora three leaf flat wire Nitinol spring, that is connected to the distalend of the hypo-tube 112 by welding or a crimp tube. Other springmembers, formed from materials such as 17-7 or carpenter's steel, mayalso be used. As noted above, signal wires 41 and 42 connect theelectrode 20 and temperature sensor elements to the PC board 38. Thespring member 116 and signal wires 41 and 42 are enclosed in a flexiblebody 118, preferably formed from Pebax® material, polyurethane, or othersuitable materials. The spring member 116 may also be pre-stressed sothat the distal tip is pre-bent. An insulating sleeve 120 may be placedbetween the spring member 116 and the lead wires 41 and 42 if desired.

[0102] The distal section 110 may, alternatively, have a malleableportion. As illustrated for example in FIG. 17A, the spring member 116(FIG. 16) is replaced with a shorter, but otherwise identical springmember 116′ and a tapered malleable member 122 that is secured to thehypotube 112 by welding or other suitable methods. In a preferredimplementation having seven electrodes, the malleable member 122 willextend to fourth electrode (counting proximal to distal), although thismay be varied depending on the intended application. The spring member116′ and malleable member 122 may be secured to one another with astainless steel crimp tube 124, which is soldered or otherwise bonded tothe malleable member and mechanically coupled to the spring member withcrimps 126. Suitable materials for the malleable member 122 includestainless steel.

[0103] The malleable portion within the distal section 110 may also beprovided in the manner illustrated in FIG. 17B. Here, the spring member116′ is secured to malleable hypotube 121 with, for example, crimps 123.The hypotube 121 is secured to the hypotube 112 by welding or othersuitable methods. One particular advantage of this arrangement is thatthe relative lengths of the malleable and flexible regions may be variedduring manufacture by simply varying the length of the hypotube 121.

[0104] Probes having distal sections with both malleable and flexibleregions may also be provided without a pull wire. The exemplary probe106′ illustrated in FIG. 17C is essentially identical to the probe 106illustrated in FIG. 14. Here, however, the pull wire 34 and outer tubing114 have been eliminated and a tip electrode 125 has been added.

[0105] Referring to FIGS. 17D and 17E, the tip electrode 125 preferablyincludes a through hole 127 that allows instrumentalities, such assuture material or one-quarter inch umbilical tape, to be threadedthrough the electrode to form a pull wire-like device if desired. Thethrough hole 127 may also be engaged by a towel clamp formed fromnon-conducting material, or other similar device, during a procedure toallow the physician to push or pull from either end of the probe 106′for positioning and pressure application purposes. For example, afterthe suture material has been used to pull the probe 106′ around an organsuch as the heart, a towel clamp may be used to grab the distal end ofthe probe for more accurate positioning.

[0106] The ends of the through hole 127 are preferably chamfered and, asillustrated in FIG. 17E, the through hole may extend straight throughthe tip electrode 125. Alternatively, as illustrated in FIG. 17F,electrode 125′ includes a through hole 127′ with two portions arrangedat an angle to one another. A lumen 129, having a large diameter portionand a small diameter portion (in which temperature sensors may belocated), extends through the base 131 and into the interior of the tipelectrode 125. The base 131 is inserted into the end of the distalsection 110 during assembly.

[0107] It should be noted that a tip electrode with a through hole, suchas those illustrated in FIGS. 17D-17F, may be used in combination withother probes, including those illustrated in FIGS. 1-13 of the presentapplication. The exemplary electrodes illustrated in FIGS. 17C-17F havean outer diameter of about 2.7 mm and are about 8 mm in length. The sizeand shape of the tip electrode may, of course, be varied as desired tosuit particular applications.

[0108] There are a number of advantages associated with probes having adistal section with both malleable and flexible regions. For example,the combination of malleable and flexible regions in the distal section110 allows a single probe to form a wide variety of lesions. Therelatively stiff, malleable region of the distal section 110 may beshaped to conform to anatomical structures on, for example, the surfaceof the heart. Direct pressure may then be applied to the structureduring the formation of continuous lesions (note lesion 152 in FIG. 26)or segmented lesion patterns. The flexible region of the distal section110 may be wrapped around anatomical structures such as, for example,pulmonary veins (note lesions 202 and 204 in FIG. 26). The malleable andflexible regions may also be used in conjunction with one another by,for example, shaping the malleable region to suit a particular procedureprior to wrapping the flexible region around an anatomical structure.

[0109] A probe with a combination of malleable and flexible regions inthe distal section 110 may also be used in combination with therelatively short outer member 48 illustrated in FIG. 8B.

[0110] IV. Operative Elements, Temperature Sensing and Power Control

[0111] In each of the preferred embodiments, the operative element is aplurality of spaced electrodes 20. However, other operative elements,such as lumens for chemical ablation, laser arrays, ultrasonictransducers, microwave electrodes, and ohmically heated hot wires, andthe like may be substituted for the electrodes.

[0112] The spaced electrodes 20 are preferably in the form of wound,spiral coils. The coils are made of electrically conducting material,like copper alloy, platinum, or stainless steel, or compositions such asdrawn-filled tubing (e.g. a copper core with a platinum jacket). Theelectrically conducting material of the coils can be further coated withplatinum-iridium or gold to improve its conduction properties andbiocompatibility. A preferred coil electrode is disclosed in U.S. Pat.No. 5,797,905.

[0113] As an alternative, the electrodes may be in the form of solidrings of conductive material, like platinum, or can comprise aconductive material, like platinum-iridium or gold, coated upon thedevice using conventional coating techniques or an ion beam assisteddeposition (IBAD) process. For better adherence, an undercoating ofnickel, silver or titanium can be applied. The electrodes can also be inthe form of helical ribbons. The electrodes can also be formed with aconductive ink compound that is pad printed onto a nonconductive tubularbody. A preferred conductive ink compound is a silver-based flexibleadhesive conductive ink (polyurethane binder), however other metal-basedadhesive conductive inks such as platinum-based, gold-based,copper-based, etc., may also be used to form electrodes. Such inks aremore flexible than epoxy-based inks.

[0114] The flexible electrodes 20 are preferably about 4 mm to about 20mm in length. In the preferred embodiment, the electrodes are 12.5 mm inlength with 1 mm to 3 mm spacing, which will result in the creation ofcontinuous lesion patterns in tissue when coagulation energy is appliedsimultaneously to adjacent electrodes. For rigid electrodes, the lengthof the each electrode can vary from about 2 mm to about 10 mm. Usingmultiple rigid electrodes longer than about 10 mm each adversely effectsthe overall flexibility of the device, while electrodes having lengthsof less than about 2 mm do not consistently form the desired continuouslesion patterns.

[0115] The electrodes 20 may be operated in a uni-polar mode, in whichthe soft tissue coagulation energy emitted by the electrodes is returnedthrough an indifferent patch electrode (not shown) externally attachedto the skin of the patient. Alternatively, the electrodes may beoperated in a bi-polar mode, in which energy emitted by one or moreelectrodes is returned through other electrodes. The amount of powerrequired to coagulate tissue ranges from 5 to 150 w.

[0116] As illustrated for example in FIG. 10, a plurality of temperaturesensors 128, such as thermocouples or thermistors, may be located on,under, abutting the longitudinal end edges of, or in between, theelectrodes 20. Preferably, the temperature sensors 128 are located atthe longitudinal edges of the electrodes 20 on the side of the structureintended to face the tissue. In some embodiments, a referencethermocouple 130 (FIG. 14) may also be provided. For temperature controlpurposes, signals from the temperature sensors are transmitted to thesource of coagulation energy by way of wires 42 (FIG. 4) that are alsoconnected to the aforementioned PC board 38 in the catheter handle.Suitable temperature sensors and controllers which control power toelectrodes based on a sensed temperature are disclosed in U.S. Pat. Nos.5,456,682, 5,582,609 and 5,755,715.

[0117] The temperature sensors are also preferably located within alinear channel (not shown) that is formed in the distal member. Thelinear channel insures that the temperature sensors will directly facethe tissue and be arranged in linear fashion. The illustratedarrangement results in more accurate temperature readings which, inturn, results in better temperature control. As such, the actual tissuetemperature will more accurately correspond to the temperature set bythe physician on the power control device, thereby providing thephysician with better control of the lesion creation process andreducing the likelihood that embolic materials will be formed. Such achannel may be employed in conjunction with any of the electrode (orother operative element) supporting structures disclosed herein.

[0118] Finally, the electrodes 20 and temperature sensors 128 caninclude a porous material coating, which transmits coagulation energythrough an electrified ionic medium. For example, as disclosed in U.S.Pat. No. 5,991,650, electrodes and temperature sensors may be coatedwith regenerated cellulose, hydrogel or plastic having electricallyconductive components. With respect to regenerated cellulose and othermicro-porous materials, the coating acts as a mechanical barrier betweenthe surgical device components, such as electrodes, preventing ingressof blood cells, infectious agents, such as viruses and bacteria, andlarge biological molecules such as proteins, while providing electricalcontact to the human body. The micro-porous material coating also actsas a biocompatible barrier between the device components and the humanbody, whereby the components can now be made from materials that aresomewhat toxic (such as silver or copper).

[0119] V. Operative Element Identification

[0120] Certain power source and control devices, such as the Cobra®electrosurgical unit manufactured by EP Technologies, Inc., allow thephysician to individually select which of the electrodes 20 will besupplied with power. In a seven electrode arrangement, for example, thepower supply and control device will include seven on-off switches thatrespectively correspond to the seven electrodes 20. Such an arrangementallows the physician to selectively enable only those electrodes that,for example, are located outside the outer member 22 after a loop hasbeen formed around an anatomical structure. Nevertheless, it can bedifficult for the physician to accurately determine how many of theelectrodes are outside the outer member 22 during a surgical procedurewhere the physician makes use of a direct line of sight into the patientbecause some of the electrodes may be located behind the anatomicalstructure.

[0121] An electrode identification system in accordance with a presentinvention may be provided to enable the physician to readily determinehow many of the electrodes are located outside of an outer member. Theidentification system, one embodiment of which is illustrated in FIG.18, includes indicia associated with the electrodes and correspondingindicia on the outer member. More specifically, the illustratedembodiment includes unique indicia (i.e. the indicia that are visuallydistinguishable from one another) 130 a, 132 a and 134 a on the distalmember 18, each of which corresponds to a particular one of theproximal-most three of the seven electrodes 20, and correspondingindicia 130 b, 132 b and 134 b on the distal portion of the outer member22. The exemplary indicia is in the form of colored rings or bands.Indicia 130 a and 130 b are black, indicia 132 a and 132 b are red, andindicia 134 a and 134 b are blue. The order of the indicia (i.e. black,red, blue) is the same on the distal member 18 and outer member 22.

[0122] The indicia is used by the physician in the following manner.When a loop is formed around pulmonary veins in the manner illustratedin FIG. 5, a number of electrodes 20 will be located behind thepulmonary veins (from the physicians perspective) and one of theelectrodes will be located immediately adjacent the distal end of theouter member 22. If, for example, the indicia associated with theelectrode 20 adjacent the distal end of the outer member 22 is the blueindicia 134 a, the physician will know by reviewing the indicia on thedistal end of the outer member that there are two electrodes proximal tothe “blue” electrode (i.e. the electrode associated with the red indicia132 b and the electrode associated with the black indicia 130 b). Giventhe fact that two of the electrodes 20 are located within the outermember 22, the physician will be able to determine that the distal-mostfive electrodes are in contact with tissue, despite the fact that one ormore of the five electrodes is not visible by direct observation becausethey are behind the pulmonary veins.

[0123] The number of electrodes that have indicia associated therewith,as well as the percentage of the total number electrodes that haveindicia associated therewith, will depend on the particular surgicalprocedure for which the identification system is intended. Other visibleindicia, such as alpha-numeric symbols or shading, may also be employed.Additionally, although the embodiment of the system illustrated in FIG.18 is shown in combination with the surgical device illustrated in FIGS.1A and 1B, other devices, such as those disclosed in the presentspecification, may also be provided with such a system.

[0124] VI. Masking

[0125] The portion of an operative element that is not intended tocontact tissue (or be exposed to the blood pool) may be masked through avariety of techniques with a material that is preferably electricallyand thermally insulating. This prevents the transmission of coagulationenergy directly into the blood pool and directs the energy directlytoward and into the tissue. This also prevents collateral damage totissue by blocking transmission of coagulation energy into adjacent,non-target tissue. In the context of epicardial lesion creation, suchnon-target tissue may include the phrenic nerve and lung tissue.

[0126] For example, a layer of UV adhesive (or another adhesive) may bepainted on preselected portions of the electrodes to insulate theportions of the electrodes not intended to contact tissue. Depositiontechniques may also be implemented to position a conductive surface onlyon those portions of the assembly intended to contact tissue. A coatingmay also be formed by dipping the electrodes in PTFE material.

[0127] Alternatively, a mask element may be positioned over a structurethat supports one or more electrodes or other operative element toelectrically and thermally insulate the desired portions thereof. Asillustrated for example in FIGS. 19 and 20, a mask element 136 inaccordance with one embodiment of a present invention includes a mainbody 138, having a side wall 140 defining an interior bore 142 and aplurality of openings 144, and a plurality of fluid retention elements146 located in the openings. The main body 138 is preferably formed frommaterial that is electrically and thermally insulating. The fluidretention elements 146 may be used to retain a conductive liquid such assaline and release the liquid during diagnostic or therapeuticprocedures. When, for example, the mask element 136 is placed over theexemplary distal member 18, coagulation energy from the electrodes 20will only be transmitted through the openings 144.

[0128] With respect to materials, the main body 138 is preferably formedfrom an elastic material that will hold the mask element 136 on thedistal member 18 or other operative element supporting structure, yetalso allow the surgeon to rotate the main body to focus the coagulationenergy, or remove the mask element altogether, as desired. A suitableelastic material is silicone rubber having a thickness that ranges fromabout 0.05 mm to about 1 mm, depending on the desired level ofinsulation. For some surgical devices, the main body 138 need only bebendable, as opposed to elastic. Here, biocompatible plastics that arecommonly used in catheters, such as Pebax® material and polyurethane,may be employed and the main body 138 secured to the surgical devicewith an adhesive.

[0129] Suitable materials for the fluid retention elements 146 includebiocompatible fabrics commonly used for vascular patches (such as wovenDacron®), open cell foam materials, hydrogels, macroporous balloonmaterials (with very slow fluid delivery to the surface), andhydrophilic microporous materials. The effective electrical resistivityof the fluid retention elements 146 when wetted with 0.9% saline (normalsaline) should range from about 1 Ω-cm to about 2000 Ω-cm.

[0130] Because it is important that the physician be able to identifythe electrodes 20 or other operative elements that are in contact withtissue, the exemplary main body 138 should either be transparent or beprovided with indicia (not shown) that allows the physician todistinguish between the electrodes. Such indicia, which may be printeddirectly onto the main body 138 with biocompatible ink, includes colorcoding, alpha-numeric indicia and shading.

[0131] Mask elements in accordance with the present invention may beused in conjunction with devices other that the shaft and spaced closedcoil electrode structure illustrated in FIG. 20. For example, the closedcoil electrodes may be replaced with open coil electrodes or a straightpiece of wire. Also, temperature sensors may be moved from theunderlying support structure to a portion of the mask element,preferably to the fluid retention elements. The temperature sensorscould be woven into fabric fluid retention material or embedded in fluidretention elements formed from other materials. Here, however,rotational movement of the mask element should be limited to, forexample, 180 degrees in order to prevent damage to the signal wires thatwill be connected to the temperature sensors.

[0132] VII. Clamp Devices

[0133] As illustrated for example in FIGS. 21-24, a clamp device 148 inaccordance with a preferred embodiment of a present invention includes aforceps-like apparatus 150 and a tissue coagulation apparatus 152. Theforceps-like apparatus 150 includes arms 154 and 156 that are pivotablysecured to one another by a pin 158 to allow the device to be opened andclosed. The proximal portions of the arms 154 and 156 may be formed fromrigid or malleable material. The arm distal portions 160 and 162, whichare curved and support the tissue coagulation apparatus 152, arepreferably formed from malleable material. This allows the arm distalportions 160 and 162 to be re-shaped by the physician as needed forparticular procedures and body structures (note the dash lines in FIG.21). Alternatively, one or both of the arm distal portions 160 and 162may be formed from rigid material. The arm distal portions 160 and 162and, preferably the entire forceps-like apparatus 150, will be coatedwith a layer of insulating material (not shown), such as heat shrinkPebax® material, polyester, or polyurethane. A pair of handles 164 and166 are mounted on the proximal ends of the arms 154 and 156.

[0134] The exemplary tissue coagulation apparatus 152 includes anoperative element support member 168 that may be formed from a soft,flexible, insulative, biocompatible thermoplastic material such asPebax® material, polyethylene, or polyurethane. In the illustratedembodiment, which may be used to form lesions around one or morepulmonary veins, the operative element support member 168 willpreferably be about 5 French to about 9 French in diameter.

[0135] Referring more specifically to FIG. 21, the operative elementsupport member 168 is a continuous structure, but for the break at thedistal end of the arm distal portions 160 and 162 that allows the deviceto be opened and closed, which will form a continuous loop around a bodystructure when the clamp device is in the closed position illustrated inFIG. 21. As such, the electrodes 20 (or other operative element)supported thereon may be used to create a continuous lesion pattern intissue when coagulation energy is applied simultaneously to theelectrodes. Additionally, the curvature of the arm distal portions 160and 162 and operative element support member 168 allow the physician toapply pressure to a body structure, such as a pulmonary vein, that isadequate to enable the formation of a single continuous transmurallesion all the way around the body structure in one step withoutcollapsing the body structure, as would be the case with a device havingstraight arm distal portions. The open region defined by the arm distalportions 160 and 162 and operative element support member 168 may besubstantially circular, oval or any other closed shaped necessary for aparticular procedure.

[0136] The operative element support member 168 is preferably mountedoff center by an angle θ on the arm distal portions 160 and 162, as bestseen in FIG. 24. In the illustrated embodiment, the operative elementsupport member 168 is approximately 45 degrees off center. Suchpositioning provides a number of advantages. For example, the off centerpositioning focuses the coagulation energy downwardly (towards theheart) and inwardly (towards the pulmonary veins) when the tissuecoagulation apparatus 152 is positioned around one or more pulmonaryveins. So positioned, with side A advanced against heart tissue, theinsulated arm distal portions 160 and 162 act as a shield to prevent thecoagulation of tissue other than that targeted for coagulation.Moreover, the physicians view of the tissue in contact with the tissuecoagulation apparatus 152 will not be blocked by the arm distal portions160 and 162.

[0137] As illustrated for example in FIGS. 21-23, an electrical conduit170 connects the tissue coagulation apparatus 152 to an electricalconnector 172 that may be connected to a source of RF coagulationenergy. More specifically, signal wires 41 and 42 from the electrodesand temperature sensors on the tissue coagulation apparatus 152 runthrough the electrical conduit 170 along the arm 156 to the electricalconnector 172.

[0138] Another exemplary clamp device, which is generally represented byreference numeral 174, is illustrated in FIG. 25. Like the exemplaryclamp device illustrated in FIGS. 21-24, clamp device 174 includes aforceps-like device 176 and a tissue coagulation apparatus 178 which,unless otherwise indicated, are essentially the same as the forceps-likedevice and tissue coagulation apparatus illustrated in FIGS. 21-24.Here, however, the proximal ends of the arms 180 and 182 are pivotablysecured to one another by a pin 184 and the handles 186 and 188 arelocated just proximally of the pin. Also, given the distance that thecurved arm distal portions 190 and 192 are capable of moving from oneanother, the tissue coagulation apparatus 178 includes a pair ofoperative element support members 194 and 196 that are connected to theconnector 172 by a pair of electrical conduits 198 and 200.

[0139] It should also be noted that the although the exemplary clampdevices illustrated above employ a forceps-like apparatus having a pairof arms connected by a pivot pin to position the tissue coagulationapparatus around tissue, other apparatus may also be employed. Forexample, an elongate apparatus including a scissors-like handle at oneend, curved distal portions at the other end, and a suitable mechanicallinkage joining the two may be employed.

[0140] VIII. Methods

[0141] In accordance with an invention herein, surgical devices such asthose describe above may be used to support an operative element on theouter surfaces of body structures for diagnostic and/or therapeuticpurposes. In the context of the treatment of atrial fibrillation, forexample, surgical devices with loop structures such as those describedabove may be used to support an operative element, such as a pluralityof spaced electrodes, that creates transmural epicardial lesions toisolate the sources of focal (or ectopic) atrial fibrillation.

[0142] Turning to FIG. 26, an exemplary method of treating focal atrialfibrillation with a device such as that illustrated in FIG. 5 involvesthe creation of transmural lesions around the pulmonary veins. Lesionsmay be created around the pulmonary veins individually or, as isillustrated in FIG. 26, a first transmural epicardial lesion 202 may becreated around the right pulmonary vein pair RPV and a second transmuralepicardial lesion 204 may be created around the left pulmonary vein pairLPV. Thereafter, if needed, a linear transmural epicardial lesion 206may be created between the right and left pulmonary vein pairs RPV andLPV. A linear transmural lesion (not shown) that extends from theepicardial lesion 204 to the left atrial appendage may also be formed.The linear lesions may be formed with the probe described above withreference to FIGS. 17A and 17C. Other suitable surgical devices forcreating linear lesions, one example of which would be the deviceillustrated in FIGS. 14-16 without the pull wire, are disclosed inaforementioned U.S. application Ser. No. 09/072,872.

[0143] Alternatively, as illustrated in FIG. 27, a single lesion 208 maybe formed around all four of the pulmonary vein pairs RPV and LPV.

[0144] Access to the heart may be obtained via a thoracotomy,thoracostomy or median sternotomy. Ports may also be provided forcameras and other instruments.

[0145] Surgical devices with loop structures such as those describedabove may also be used to create transmural epicardial lesions in a mazepattern that controls electrical propagation within the left and rightatria. More specifically, a maze pattern may be created by positioning aplurality of spaced electrodes, or other operative element, within thepericardial space around the exterior of the heart at the variouslocations needed to form the desired lesion pattern.

[0146] The surgical devices described above may also be urged throughtissue planes (i.e. the space between fascia material and a particularorgan) to properly position the device prior to the actuation of theoperative elements. Such a procedure is referred to as blunt dissection.

[0147] The clamp devices illustrated in FIGS. 21-25 may also be used toform lesions such as pulmonary vein lesions 202, 204 and 208, or lesionsaround other body structures.

[0148] Although the present inventions have been described in terms ofthe preferred embodiments above, numerous modifications and/or additionsto the above-described preferred embodiments would be readily apparentto one skilled in the art. It is intended that the scope of the presentinventions extend to all such modifications and/or additions and thatthe scope of the present inventions is limited solely by the claims setforth below.

We claim:
 1. A surgical device, comprising: a relatively short shaftdefining a distal end and a proximal end; a handle associated with theproximal end of the shaft; a distal member associated with the distalend of the shaft including a flexible region and a malleable region; andan operative element carried by the distal member.
 2. A surgical deviceas claimed in claim 1, wherein the shaft is malleable.
 3. A surgicaldevice as claimed in claim 1, wherein the shaft is rigid.
 4. A surgicaldevice as claimed in claim 1, wherein the operative element comprises aplurality of spaced electrodes extending over the flexible region andthe malleable region.
 5. A surgical device as claimed in claim 1,wherein the flexible region is located distally of the malleable region.6. A surgical device as claimed in claim 1, wherein the distal memberforms part of a loop structure.
 7. A surgical device as claimed in claim1, further comprising: a pull wire defining a distal end associated withthe distal member and a proximal end associated with the handle.
 8. Asurgical device as claimed in claim 7, further comprising: a tubularmember positioned around a predetermined portion of the shaft andcovering a portion of the pull wire.
 9. A surgical device as claimed inclaim 1, further comprising: a pull wire associated with the distalmember.
 10. A surgical device as claimed in claim 1, wherein theoperative element comprises a tip electrode having a pair of exterioropenings.
 11. A surgical device as claimed in claim 10, wherein theexterior openings are connected by a through hole extending through thetip electrode.
 12. A surgical device, comprising: a shaft defining adistal region and a proximal end; a handle associated with the proximalend of the shaft; and an electrode carried by the distal regionincluding a pair of exterior openings.
 13. A surgical device as claimedin claim 12, wherein the exterior openings are connected by a throughhole extending through the electrode.
 14. A surgical device as claimedin claim 12, wherein the distal region defines a distal end and theelectrode comprises a tip electrode.
 15. A surgical device as claimed inclaim 14, further comprising: a plurality of spaced electrodes carriedby the distal region proximal to the tip electrode.
 16. An electrode foruse with a surgical device, comprising: a main body portion; and a pairof exterior openings formed in the main body portion without anystructural member therein.
 17. An electrode as claimed in claim 16,wherein the exterior openings are connected by a through hole extendingthrough the electrode.
 18. An electrode as claimed in claim 17, whereinthe main body portion defines a longitudinal axis and the through holeis substantially perpendicular to the longitudinal axis.
 19. Anelectrode as claimed in claim 17, wherein the through hole issubstantially linear from one exterior opening to the other.
 20. Anelectrode as claimed in claim 17, wherein the through hole issubstantially v-shaped.